Appendix A, which forms a part of this disclosure, is a list of commonly owned copending U.S. patent applications. Each one of the applications listed in Appendix A is hereby incorporated herein in its entirety by reference thereto.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of the Invention
The invention relates to computer equipment and, in particular, relates to a system and a method for sensing and controlling the speed of one or more cooling fans used to cool personal computers.
2. Description of the Related Art
As personal computers have become increasingly sophisticated, there has been an increased need for cooling devices which will remove ambient heat from the air surrounding the electronic components, of the personal computer. Specifically, as personal computers have become increasingly sophisticated, these computers are using increased numbers of electronic components each of which produce greater amounts of heat. This heat can result in damage to components within the chassis or casing of the personal computer or can also result in a decrease in the longevity of the electronic components.
Therefore, it is desirable to reduce the amount of ambient heat in and around the electronic components comprising the personal computer. Various devices are used to reduce or remove the heat. For example, heat sinks are often attached to heat generating electronic components, such as microprocessors, and fans are also used for forced air cooling of the electronic components. Specifically, fans are used to blow air over the heat generating electronic components and also to blow the accumulated hot air away from the atmosphere surrounding the components to thereby lower the air temperature and allow for more heat to be radiated out of the component.
Generally, it is desirable to operate the fans at the lowest speed possible that still provides adequate cooling. Slower speed of operation prolongs the longevity of the fan and also decreases the noise generated by the personal computer. In some applications, there can be as many fans simultaneously operating to cool the computer. At high speed operation, the noise generated by these fans would be distracting to the computer user. Hence, there is a desire to use fans that operate at lower speeds and still provide adequate cooling.
Moreover, in many personal computers, a plurality of fans are used to cool the chassis section of the personal computer. Generally, the number of fans is selected to provide a desired amount of forced air cooling with some redundancy. The redundancy is provided so that if one or more of the fans fail, adequate cooling can still be provided by the remaining fans. This redundancy, however, increases the overall cost of the computer as more fans are installed than are actually needed for normal cooling operations. Further, it will be appreciated that when all of the fans are operating, the fans are generating an increased amount of noise.
Many personal computers are also equipped with dual or multi-speed DC fans that operate at different speeds depending upon the ambient conditions within the personal computer. This allows a controller to select the speed for the fans that provide the optimum cooling without using excessive power or causing excessive wear on the fans. Unfortunately, these multi-speed fans are more expensive and increase the overall cost of the personal computer. In the highly competitive market of personal computers, a small increase in the component cost can result in a significant effect on the overall profitability of the sale of the personal computer. Consequently, it is desirable to be able to use the least expensive components that are capable of performing the necessary functions.
Moreover, while multi-speed fans are currently available for use with personal computers, if one of these fans fail, the prior art personal computers are often unable to detect the failure and to take corrective action. While multi-speed fans can be used to provide varying cooling capacity within the personal computer chassis, these systems are not generally capable of accommodating a failure of one or more of the fans. Hence, the multi-speed fans are also generally selected so as to provide more cooling capacity than is actually required to account for the subsequent loss of one or more fans. This of course causes greater power drain on the power supply, results in noisier computers and also decreases the longevity of the fans themselves.
Hence, there is a need for an inexpensive cooling fan system which is capable of adequately cooling a personal computer. To this end, there is a need for a cooling fan system which can operate at different speeds to provide varying cooling capacity that is less expensive and simpler in construction than systems that have been previously available. There is also a need for an inexpensive cooling fan system for a computer that is capable of determining when one or more of the fans in the cooling fan system has failed and then of inducing other fans to increase their speed to account for the loss of the one or more fans.
The aforementioned needs are satisfied by the method of controlling a fan speed control system provided herein. In one aspect, the invention is comprised of a method of cooling a computer. The method is comprised of operating a plurality of fans of a first speed wherein the plurality of fans are positioned so as to cool components within the computer, sensing the operation of the plurality of fans to ensure that each of the plurality of fans is operating at the first speed, determining that at least one of the plurality of fans is operating at a speed other than the first speed, and inducing the fans other than the at least one fan to operate at a second speed selected so as to provide sufficient cooling capacity to at least partially offset the loss of cooling capacity caused by the at least one fan operating at a speed other than the first speed. In one embodiment, the step of operating a plurality of fans at the first speed comprises providing a first voltage to the fan from a power source through a fixed voltage divider. In another embodiment, the fixed voltage divider is comprised of a zener diode voltage divider. In one embodiment of the invention, the step of operating the plurality of fans at a second speed comprises inducing a switch that is connected between the voltage source and the plurality of fans so as to be connected in parallel with the fixed voltage divider to close so as to apply a second voltage, which is greater than the first voltage to the plurality of fans so as to induce the fans to operate at the second speed.
In another aspect of the invention, a method of cooling a computer is provided. The method is comprised of operating a plurality of fans at a first speed wherein the plurality of fans are positioned so as to cool components within the computer, sensing the operation of the plurality of fans to ensure that each of the plurality of fans is operating at the first speed, determining that at least one of the plurality of fans is operating at a speed other than the first speed, inducing the fans other than the at least one fan to operate at a second speed selected so as to provide sufficient cooling capacity to at least partially offset the loss of cooling capacity caused by the at least one fan operating at a speed other than the first speed, sensing the operation of the at least one fan that is not operating at the first speed, determining if the at least one fan is capable of operating at the first speed, and inducing the plurality of fans to operate at the first speed upon determining that the at least one fan is capable of operating at the first speed. In one embodiment, the step of operating the plurality of fans at the first speed comprises providing a first voltage to the fan from a power source through a zener diode fixed voltage divider. In one embodiment, the step of operating the plurality of fans at a second speed comprises inducing a switch to close that is connected between the voltage source and the plurality of fans, so as to be connected in parallel with the fixed voltage divider, to close so as to apply a second voltage, which is greater than the first voltage, to the plurality of fans so as to induce the fans to operate at the second speed.
In another aspect of the invention, a method of cooling a computer is provided. The method is comprised of the steps of providing a first voltage to the plurality of fans from a voltage source through a fixed voltage divider so that the fans operate at a first speed, sensing the speed of operation of the plurality of fans, determining if at least one fan is operating at a speed other than the first speed, and providing a second voltage to the plurality of fans upon determining that at least one fan is operating at a speed other than the first speed, wherein the second voltage induces the remaining fans to operate at a second speed, which is greater than the first speed, so as to at least partially offset the loss of cooling capacity caused by the at least one fan operating at a speed other than the first speed. In one embodiment, the step of providing a first voltage to the plurality of fans from a voltage source is comprised of providing the first voltage from the voltage source to the plurality of fans through a zener diode fixed voltage divider. In another embodiment, the step of providing a second voltage to the remaining fans comprises closing a switch that is connected between the voltage source and the plurality of fans so as to be connected in parallel to the fixed voltage divider so that substantially all of the output voltage provided by the voltage supply is applied directly to the remaining fans.
In another aspect of the invention, a method of cooling a computer is provided. The method is comprised of the steps of operating a plurality of fans so as to provide a first degree of cooling capacity to the computer, sensing the operation of each of the plurality of fans, determining if at least one of the fans is operating in a manner wherein the fan is not providing a desired degree of cooling capacity, inducing at least one operating fan, other than the at least one fan that is not providing the desired degree of cooling capacity, to increase the cooling capacity provided by the at least one operating fan. In one embodiment, the method is further comprised of the steps of sensing the operation of the at least one fan that is not operating so as to provide the desired degree of cooling capacity, determining if the at least one fan is capable of operating so as to provide the desired degree of cooling capacity, and inducing the at least one operating fan to decrease its cooling capacity. The objects and advantages of the invention will become more fully apparent from the following description taken in conjunction with the accompanying drawings.